Precast panels of various sizes and shapes are widely used as cladding on building walls, serving as components of building envelope systems intended to prevent infiltration of rain and outside air into the building. Precast cladding panels are commonly made of concrete, but may also be made with other cast materials known in the construction field. Concrete cladding panels are common on large structures such as office buildings, but they are also used on residential housing structures as an alternative to traditional cladding materials such as wood siding and brick.
Whether installed on large or small buildings, it is desirable for cladding panels to be mounted in such a way that there will be a continuous air space between the rear (i.e., inner) faces of the panels and the supporting structure, while at the same time providing reliable structural support for the panels, both to transfer the vertical weight of the panels to the supporting structure and to provide anchorage against lateral forces (such as wind) that may act on the panels.
The purpose of the air space is to provide a passage through which any water or moisture vapour that gets behind the cladding can be directed away from the building envelope before it infiltrates other parts of the building. Although caulking or other sealant materials are typically used to seal the spaces between cladding panels, the possibility of moisture infiltration behind the cladding—as a result of vapour migration, direct penetration of rainwater (due to sealant deterioration or other factors), or leakage at roof-to-wall junctures—cannot be entirely eliminated. If such moisture is not removed from the building envelope fairly promptly, it will tend to migrate further into the building, potentially causing a variety of problems that could entail costly maintenance and repairs and could detract from the building's overall durability and value. Such problems may include drywall damage due to moisture absorption, rot and mold in wooden construction components (e.g., studs and sheathing), corrosion of non-rust-resistant construction hardware, and staining on interior building finishes.
When an air space is provided behind the cladding, moisture can run downward behind the cladding to exit points such as weepholes built into the cladding system at appropriate locations. The air space also facilitates or enhances air circulation behind the cladding, helping to remove moisture vapour before it can condense inside the wall structure, and helping to dry out any wall structure components that may have become damp due to moisture infiltration.
One of the challenges facing designers of cladding panel support systems is to provide hangers or brackets that can adequately support weight of the panels at a distance away from the face of the supporting structure (i.e., so as to provide the desired air space), without significantly impeding the passage of water or water vapour through the air space. In this regard, it is particularly desirable to avoid or minimize hanger-to-panel connection details where moisture might become trapped or which might impede the downward vertical flow of moisture along the back of the panel. Depending on design preferences and panel manufacturing process constraints, hangers for precast cladding panels can be mechanically mounted to the panels after the panels have cured (such as by means of bolts, or by field-welding to mounting plates embedded in the panels), or they can be embedded into the panels during the panel-casting process.
It is desirable for precast cladding panels to be stackable as compactly as possible to minimize space requirements during storage and shipping. Accordingly, it is desirable for precast cladding panels to be configured such that they can be stacked in a way that minimizes or substantially eliminates space between stacked cladding panels, thus minimizing storage space requirements.
For the foregoing reasons, there is a need for improved precast cladding panel systems and hanger systems that enable secure mounting of panels at a uniform distance away from a vertical supporting structure without introducing significant impediments to air flow and moisture flow through the air space thus created between the panels and the supporting structure. In addition, there is a need for improved cladding panel hangers that can be embedded in precast panels during the casting process and which, although protruding from the finished panels, do not significantly impede the ability to stack the panels with minimal if any space between adjacent panels in the stack. The present disclosure is directed to these needs.